The present invention relates to a load hook arrangement, comprising a carrying element for a load, the carrying element being pivotable between a closed position and an open position. The present invention relates in particular to such a load hook arrangement as can be used for carrying a load by means of a helicopter or other similar aircraft.
Load hooks (also known as cargo hooks) are commonly used when loads are to be transported by means of helicopters and other similar aircraft. For this purpose a cable with a load hook arrangement on one of its ends is fastened to the helicopter which is equipped with a mechanical and/or an electrical release device for the load. Such load hook arrangements are very useful for transporting loads in mountain regions, for example, where no roads exist or where roads cannot be used for any reason (e.g. due to extreme weather conditions in winter). Use of load hook arrangements is thus very popular in logging. In addition, loads are often carried by means of helicopter aircraft for military purposes or in construction, where the load can be of any kind of material or even people. Finally, load hook arrangements are used for transporting casualties (e.g. people lost and injured in the mountains) or for carrying fire extinguishers in major forest fires.
A conventional load hook arrangement usually includes a carrying element (load beam) which can pivot between two positions. In its open position, one end of the carrying element is turned away from the housing of the load hook arrangement, and a load ring attached to a cable with the load can be placed on the carrying element. In its closed position, the end of the carrying element is located such that the attached load ring is blocked between the carrying element and the housing of the load hook arrangement. The load transported by means of helicopter and carried by load hook arrangements can weigh several tons, depending on the type of helicopter and the purpose of transport. It is thus clear that load hook arrangements have to be designed and constructed in such a way as to be able to carry a load with a high degree of safety, where in particular the carrying element is securely blocked in the closed position. Therefore, a conventional load hook arrangemen't also includes a blocking element which is used to block the carrying element in the closed position. This blocking element can usually switch between a blocking position, in which it maintains the carrying element in its closed position, and a releasing position, in which the carrying element is allowed to pivot from the closed position to the open position.
When a load is to be transported, the blocking element is brought into the releasing position in order to allow the carrying element to come into the open position, in which the load ring of the cable is attached to it. Then, the carrying element is brought into the closed position and blocked again by the blocking element. A spring (or another similar mechanical element) is responsible for the constant correct positioning of the blocking element in the conventional load hook arrangements. This spring holds the blocking element by default in the blocking position, unless an exterior force is applied. In such a way, the pivoting of the carrying element from its closed position to its open position always requires a deliberate action of an operator, which increases the security of the load hook arrangement significantly.
However, a load attached to a cable usually does not remain stable under the helicopter during transport, but normally oscillates and rotates on the supporting cable. This can give rise to severe safety problems, as the one end of the cable can come into a position where it exerts pressure on the blocking element. In such a situation, as a result of very high forces, the blocking element can easily be brought into the releasing position. As the carrying element is then no longer held in its closed position, it pivots into the open position due to gravity and the supported load weight, and the carried load can simply fall off. Such disasters have occurred, where the price to pay was either serious material damage or loss of human life.
A prior art arrangement is described in United States patent document U.S. Pat. No. 3,845,978 (Huber), which discloses a load hook with a carrying element latched into place by a swivelling latch element, and a first locking element which prevents the latch element from opening accidentally and thereby releasing the load hook. In U.S. Pat. No. 3,845,978, the first locking element is remotely operated by means of a motor described as an electrical solenoid bell crank. The arrangement of U.S. Pat. No. 3,845,978 also includes a second blocking element—an override pin which an operator can manually insert into a hole in the mechanism to manually block the release mechanisms and thereby prevent accidental release of the load by the helicopter pilot or due to sudden rotation of the load hook caused by, for example, turbulence or impact.
However, the manual override pin arrangement of the load hook of U.S. Pat. No. 3,845,978 means that, once the override pin is inserted, the helicopter pilot no longer has the ability to release the load. It is important for the pilot to be able to release the load if for example, the helicopter encounters flight problems, or if the load itself endangers the helicopter by becoming unstable, or by becoming entangled in an obstacle or by catching fire. It is also important for the pilot to be able to release the load, without landing, at a site where no ground staff are present to assist with disconnecting the load from the load hook.
It is desirable to propose a new and improved load hook arrangement that does not have the above-mentioned drawbacks of the state of the art. In particular, it is desirable to propose a new load hook arrangement, in which the carrying element (load beam) can be secured such that the load can be safely carried in any situation.
According to an aspect of the present invention, a load hook arrangement comprises carrying element for carrying a load, the carrying element being pivotable between a closed position and an open position a pivoting mechanism for blocking or allowing the pivoting of the carrying element into its open position, the pivoting mechanism comprising a first blocking mechanism, the first blocking mechanism being pivotable between a blocking position for blocking the carrying element in its closed position and a releasing position for allowing the carrying element to pivot into its open position, a rotating arm element for blocking or allowing, under remote control of an operator, the first blocking element to pivot to its releasing position, a motor element for actuating the rotating arm element, and a second blocking element for blocking movement of the motor element, the second blocking element being remotely controllable by an operator.
The advantage of such a load hook arrangement is, among others, that the carrying element (i.e. the load beam), when carrying the load, is doubly secured in its closed position by the second blocking element in that it prevents the rotation of the motor element.
In an embodiment variant, the second blocking element acts on motor element which controls the rotating arm, whereby the second blocking element in its blocking position blocks the rotation of the motor element, which blocks the rotating arm, which blocks the carrying element. This embodiment variant has the particular advantage, among others, that the second blocking element does not act directly on the carrying element, but on the rotating arm which controls the pivoting of the carrying element. In this way, the first and second blocking elements use different blocking techniques in order to safely block the carrying element in its closed position. Owing to these different blocking techniques, the probability of a simultaneous failure of both blocking elements can be kept very small.
In another embodiment variant, the second blocking element is remotely controllable by an operator by means of a first control mechanism. The advantage of such an embodiment variant is, among other things, that the operator (i.e. the pilot from the cockpit of the helicopter or a person on the ground in charge of the correct positioning and attachment of the load) is able to control the functioning of the second blocking element remotely. The pilot might have a button which would allow him to control the second blocking element. In such a way, the pilot would not depend on any ground staff, and could check the correct position and blocking of the carrying element before starting the aircraft. On the other hand, the first control mechanism could also be activated by a person on the ground by means of another button or similar activating means, which could be useful when a double check is required.
In a further embodiment, the second blocking element is a magnet brake. The advantage of this embodiment is, among others, that the blocking of the carrying element can be achieved in a very simple way, but guaranteeing a high degree of safety at all times. Magnet brakes are known in the art as being simple to use and maintain, but having a very small degree of failure. The use of electrically controllable magnet brakes to impede rotational movement is known in other technical fields such as in automobiles—see for example U.S. Pat. No. 5,543,672 (Nishitani).
In particular, this magnet brake can be achieved in such a way as to automatically prevent the rotating arm from pivoting, and thereby prevent the release of the carrying element as long as an external releasing is not applied to the magnet brake. It makes use of brake discs, for example, or similar elements based on magnetic forces between the pivoting mechanism and the brake discs. In such a way, a blocking effect is automatically achieved, and it is only when the pivoting mechanism for pivoting the carrying element is to be activated that the blocking is released by means of the first control mechanism. Again, safety during load transport can thus be increased significantly.
In another embodiment of the present invention, the load hook arrangement further comprises a latch element pivotable between an open position, in which a load can be removed from the load hook, and a third blocking element for blocking the latch element in its closed position. The advantages of this embodiment is, inter glia, that the latch element can be secured by a third blocking mechanism, thus improving even more the safety of the load hook arrangement according to this embodiment of the present invention. In particular, the latch element can be achieved as a toggle which can pivot between a position in which the load ring cannot be released and a position in which the load ring can be removed freely. This latch element can, for example, be kept in the blocking position by means of a spring or another similar device. In order to move this toggle against the force of the spring, an exterior force is required, which can be supplied by means of an actuator (i.e. a cable). It is also conceivable to have this latch element blocked for any movement in a particular direction (i.e. by a stopper integrated in the housing) and allow the movement only in the opposite direction. In such a constellation, the latch element could also be brought into the releasing position by the load ring during its insertion onto the load. The third blocking element can in such a situation completely block the movement which would lead to a release of the load ring.
In a further embodiment, the third blocking element is able to be actuated by means of an actuating mechanism. The advantage of this embodiment is, among others, that the blocking of the latch element (toggle) can be controlled through actuation of the third blocking element. There is also a further increase in the safety of the load hook arrangement, as the possibility of pivoting of the carrying element from the closed position into the open position is further reduced.
In another embodiment, the actuating of the third blocking element is remotely controllable by an operator by means of a second control mechanism. The advantage of this embodiment of the present invention is, inter alia, that also the functioning of the third blocking element can be controlled remotely by an operator (i.e. the pilot from the cockpit of the helicopter or a person on the ground in charge of the correct positioning and attachment of the load). The pilot might have another button which would allow him to control both the second and the third blocking elements for checking the correct position and blocking of the carrying element before starting the aircraft.
In a further embodiment, the actuating mechanism comprises a weight sensor for detecting the presence of the load, by means of which sensor the actuating mechanism is controllable. This embodiment has the advantage, among other things, that the actuating mechanism for actuation of the third blocking element can be controlled in a fully automated way. In particular, the weight sensor can detect the presence of the attached load and initiate by itself the actuating of the actuating mechanism which consequently moves the third blocking element into the blocking position. Once the load is on the ground, i.e. once the weight sensor detects the absence of the corresponding gravitational force acting on the carrying element, it makes the actuating mechanism move the third blocking element into the releasing position, whereby movement of the latch element is again made possible. In such a way, not only is the safety of the load hook arrangement once again increased significantly, but its handling is drastically simplified.
In yet another embodiment, the third blocking element is an eccentric. The advantage of this embodiment is, among others, that the latch element can be blocked in its blocking position by means of a simple mechanical device. The actuating mechanism pivots the eccentric such that it changes its position relative to the latch element. In such a way, the movement of the latch element (toggle) is made completely impossible, so that an accidental release of the load attached to the load hook arrangement due to a pivoting of the latch element into its releasing position is completely impeded. With use of an eccentric as a third blocking element, its position then impedes completely any movement of the latch element out of its blocking position, such that no release of the load ring is possible. Of course, this again increases the overall safety of the load hook arrangement according to this embodiment of the present invention.
In still another embodiment, the load hook arrangement comprises an emergency release mechanism. The advantage of this embodiment is, among other things, that the carrying element can be brought quickly into the open position if an emergency situation should arise. In this situation, the pilot of the helicopter or any other person could release the attached load in order to prevent crash of the aircraft or injury to people on the ground. Such an emergency release mechanism could be based on mechanical, electrical, hydraulic or other elements, which allow release of all the different blocking elements and thus enable the pivoting of the carrying element into the open position for releasing the attached load.